206 



Adventures in Scenery 



Other erratic boulders belonging in all probability to the 

 same early glaciation lie near the east base of Sentinel Dome. 

 Some of them, conspicuous for their large size, are close to the 

 trail that leads to the Dome. They are strung out at intervals 

 of 100 feet or more in an irregular line that curves from the 

 Dome southeastward to the north end of Illilouett Ridge. 

 These boulders are isolated, and are surrounded by finer glacial 

 debris, whereas the steep slope below is heavily cloaked with 



Photo by F. C. Calkins, U. S. Geol. Survey 



FIG. 63. Sentinel Dome. Massive granite rock, rounded by exfoliation 

 (casting off of successive shells by weathering). The small speck at the top 

 is the Jeffrey Pine, twisted and bent by the wind shown in figure 64. 



such material of the El Portal stage. It can hardly be otherwise 

 therefore than that the boulders are the last vestige of a once 

 continous moraine that was deposited by the ice during a stage 

 much earlier than the El Portal. This very early stage of gla- 

 ciation is referred to as the Glacier Point stage. 



Glacial Deposits Near Glacier Point 



Of interest to the tourist, as to the student of geology, are 

 the glacial deposits near Glacier Point, for they answer the 



